Mac's are good machines...no question there but if the computer manufacturer IS the software company as well and has complete access to all the technical info, specs and codes....then there should be NO problems what-so-ever regarding software lockups or crashes. Given the fact that Mac's do crash and lockup and the amount of "fixes" posted by Apple (well over 3GIG's worth this year so far), I'd have to say that Mac's are more vulnerable than PC's. Don't forget that a PC gets its' hardware and software from around the world....a far bigger task for Microsoft and suppliers.
NB: Like I said, Mac's are good machines (I love the monitors) but they are far from perfect. Why anyone should be surprised (I'm not pointing any fingers, nothing personal intended) when someone talks about problems with a Mac is beyond me.